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The threaded flange is a type of flange that connects the pipes with threaded. In threaded flange, the pipes do not connect with any kind of welding method. Rather the pipes are connected with a wench and threads. To tighten the gap on the threads of the pipes and the flanges, thread tapes are used on the pipes. Threaded flanges are almost similar to the slip-on flanges and also similar to the socket weld flanges. But the main difference is, threaded flanges use screws inside them to connect the pipes. Here, the pipe’s an outside bore and the flange’s inside bore needs to be the same size. The pipes also have similar threads on the outer layer that responds to the inner layer of the flanges. And most of the times special seals are applied to join the pipes with flanges.

You will be able to find threaded pipe and pipe fittings with a variety of sizes but it is mostly used for pipes with less than 4 inches of diameter. Also, the threaded system is not applicable for pipes that has a thin wall because thin walls cannot be used to make threads.

There are mainly two types of threaded flanges.

Raised Face Flange: When a threaded flange has a long gasket area, then it is called a raised face flange. The raised gasket means that the flange is raised to cover a long area. It is usable with a variety of pipes and other fittings. Usually, the raised face is used on a point where the pressure is extremely high. The pressure can be concentrated into one point and therefore, the seal remains tight. It helps to keep the seals intact. The height mainly varies based on the pressure. For pressure range 150-300, the height is 1.6mm and for 400-2500 the height should be 6.4mm.

Ring Joint Flange: The ring joint system comes with a grooved ring on the flange which is used on metal to metal connection. The groove fits a metal gasket which does not wear out easily. Especially when the pressure is high, this kind of grooved flanges are useful. The metal gasket does no wear out and makes a strong seal with metal flange and metal pipe connection.

Installation and Maintenance

The threaded system requires the pipe’s outside diameter to be equal to the inside diameter of the flange. It is like the socket weld system. The inside of the flange and the outside of the pipe contains threads. These threads are cut using special machines. Then the threads of the pipes are screwed on the threads of the flange. Threaded system does not need to be welded. So the installation is simpler and convenient.

Threaded pipes and fittings are useful for places where welding is not applicable. Most of the time galvanized pipes and fittings cannot be taken under the welding process as it affects the anti-rust capability. In these cases, the threaded system becomes the solution. However, the threaded system is not useful for temperatures between -45 degrees and 260 degrees Celsius.